function moment = M_pq( Image, p, q )
%geometric moment of order p + q
% M_pq = sum(over x) sum(over y) f(x,y) * x^p * y^q
% f(x,y) is grayscale value of image in location (x,y)
xs = 1: size(Image,2);
ys = 1:size(Image,1);
xs = xs .^p;
ys = ys .^q;
moment = sum(sum( (ys' * xs) .* double(Image)));